This artist's concept shows the pole-to-pole orbits of NASA's Juno spacecraft at Jupiter.

NASA/JPL-Caltech/SwRI SCOTT BOLTON - 2

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Originally published on July 10, 2017 10:33 am

Scientists are about to get an up-close and personal look at the planet Jupiter's most famous landmark, the Great Red Spot.

NASA's Juno spacecraft will be directly over the spot shortly after 10 p.m. ET Monday, July 10, about 5,600 miles above the gas giant's cloud tops. That's closer than any spacecraft has been before.

The spot is actually a giant storm that has been blowing on Jupiter for centuries. It's huge, larger than Earth in diameter.

"It's lasted a really long time," says Scott Bolton of the Southwest Research Institute in San Antonio and principal scientist for NASA's Juno mission to Jupiter. "No scientists really understand exactly how that storm is created or why it could last so long."

Not only will Juno's camera be able to capture detailed images of the spot, but the probe also carries scientific instruments that can provide additional details about the storm. For example, the microwave radiometer can peer through the clouds and see what kinds of atmospheric structures underpin the spot.

"It's possible that the roots are quite deep," says Bolton. "So we'll be able to take a look at that and see what's underneath the cloud tops."

Bolton and his colleagues are planning to bring a lot of astronomical resources to bear during this flyby. Ground-based telescopes, Earth-orbiting telescopes, even amateur astronomers will be taking measurements of the planet around the time Juno gets there to provide as complete a picture of the storm as possible.

This isn't the last time Juno will pass over the spot. Once every 53 days the spacecraft's orbit takes it close to the planet. Each future flyby of the Red Spot will focus on a different kind of science.

Another Juno instrument can measure the gravity field around the spot. Bolton says there may be something massive below the spot that's contributing to its existence.

"Maybe there's a blob going around Jupiter that's underneath the Red Spot, and we may be able to see that," he says.

Imagine that. The Great Red Spot may have a Great Big Blob associated with it.

Juno's main antenna will be pointed away from Earth during the closest approach, so it will be a few days before the data and pictures stored on board can be downlinked to Earth.

Bolton is confident the images will be eye-popping when they arrive.

"Jupiter is stunning when you get near it," he says.

Copyright 2018 NPR. To see more, visit http://www.npr.org/.

MARY LOUISE KELLY, HOST:

A gigantic storm has captured scientists' interest for more than a century, but no one's been able to get a really close look at it until now. That's because the storm is on Jupiter. It's better known as Jupiter's Great Red Spot. The close-up look is being provided by NASA's Juno spacecraft, which is orbiting around the planet. NPR science correspondent Joe Palca has this preview of what scientists are hoping to learn about the storm.

JOE PALCA, BYLINE: Juno is flying closer to Jupiter than any space probe has before.

SCOTT BOLTON: Jupiter's stunning when you get near it.

PALCA: Scott Bolton is principal investigator for the Juno mission. He spoke with me from his office at the Southwest Research Institute in San Antonio. Every 53 days, Juno's orbit brings it to within a few thousand miles of Jupiter's cloud tops. Today, the orbit takes it over the Great Red Spot.

BOLTON: We're flying right over it, pretty much.

PALCA: The spot is huge - bigger in diameter than the Earth. Bolton says in addition to taking close-up pictures, one of Juno's instruments can peer through the clouds and see what's underneath the spot - something scientists would dearly like to know.

BOLTON: I mean, it's lasted a really long time. No scientists really understand exactly how that storm was created or why it could last so long. It's possible that the roots are quite deep. And so we'll be able to take a look at that and see what's underneath the cloud tops.

PALCA: This isn't the only time Juno will fly directly over the spot.

BOLTON: Each time, we'll focus on a different kind of science.

PALCA: In a future flyby, Juno will measure the gravity field around the spot. Bolton says there may be something massive below the spot that's contributing to its existence.

BOLTON: Maybe there's a blob going around Jupiter that's underneath the red spot. And we may be able to see that.

PALCA: The blob beneath the spot - that's great.

BOLTON: (Laughter).

PALCA: The first photos and data from this latest flyby should arrive on Earth later this week. Joe Palca, NPR News. Transcript provided by NPR, Copyright NPR.